Abstract: Objective To estimate the demineralization of anterior primary teeth pretreated by NaF-chitosan gel and to discuss the potentiality of NaF-chitosan gel for early stage caries treatment. Method NaF-chitosan gel was prepared, and its basic performance observed; NaF-chitosan gel's F ion release rate was tested. Anterior primary teeth samples were prepared and divided into 4 groups randomly. Three groups were pretreated with Duraphat, NaF-chitosan gel and chitosan gel respectively. The 4th group was the blank control group. All samples were demineralized with lactic acid. The liquid was collected and its Ca²⁺ ion concentration was tested. The calcium ion concentration was measured by ion flame method. The variance of Ca²⁺ ion concentration in different groups was analyzed with SPSS 19.0. Results NaF-chitosan gel was light yellow clear liquid at room temperature. It changed into ivory jelly gel at 37 ℃. NaF-chitosan gel could release fluorine ion 70.22% in 4 h. There was no difference between NaF-chitosan gel (4.29 mg/L) and gold standard duraphat (4.22 mg/L) in reducing demineralization by lactic acid. The Ca²⁺ ion concentration was much lower in NaF-chitosan gel group than in chitosan gel (7.20 mg/L) and control group (7.34 mg/L) (P<0.05). Conclusion NaF-chitosan gel can improve the anti-acid ability of enamel in anterior teeth, and it can be used to prevent early caries of anterior teeth.

Key words: chitosan gel, NaF, primary teeth, enamel, demineralization resistance